Silicon-Tethered 1,3-Dipolar Cycloaddition of 4-Hydroxy-2-isoxazoline 2-Oxides

Righi, Paolo; Marotta, Emanuela; Landuzzi, A.; Rosini, Goffredo

doi:10.1021/ja961816w

Cited by 48 publications

(17 citation statements)

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“…[13] Again the intramolecular 1,3-dipolar cycloaddition occurs spontaneously under the very mild reaction conditions employed. [14] It should be noted that in the large majority of the cases the product is obtained in a rather pure form and needs no further purification. Abstract in Italian: Viene presentato un nuovo approccio alla sintesi di composti aminopoliossidrilati lineari, basato su un rapido assemblaggio di un sistema eterotriciclico polifunzionalizzato e la sua apertura selettiva.…”

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Linear Aminopolyhydroxylated Structures Through Rapid Domino Assembly of a Highly Functionalized Heterotricyclic System and Its Selective Cleavage

1998

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This paper presents a new approach to linear aminopolyhydroxylated structures, based on the rapid assembly of a highly functionalized heterotricyclic system and its cleavage. The complex tricyclic structure is obtained by a sequence of two mild tandem reactions: the first involves a base-promoted nitroaldol-intramolecular cyclization between an activated primary nitroalkane and an aldehyde bearing a leaving group on the a-carbon atom to give 4-hydroxy-2-isoxazolines-2-oxides. In the second tandem process, the 4-hydroxy group was used as an anchor to link an olefinic residue (either an allyl group or a vinylsilane), which then gave rise to a spontaneous intramolecular cycloaddition with the nitrone moiety of the 2-isoxazoline-2-oxide to afford a complex tricyclic structure. These two tandem processes could be condensed into a single three-component domino reaction, which starting from the three acyclic substrates realizes a big jump in molecular complexity through the selective formation of five new bonds and four new chiral centers all concerted as a dynamic continuum in which every event depends on all the others. The second part of this project dealt with the cleavage of the tricyclic structure to unmask the target linear compounds.The richness of functionalities that were selectively installed on the tricyclic structures was screened for possible cleavages. Methods to reduce the exocyclic ester group, hydrogenolyse the bicyclic nitroso acetal, and hydroxydesylilate the cyclic silyl ether were found. In addition, during the early attempts of linearization of the tricyclic compounds, unexpected clean fragmentations of the products were observed, some of them affording synthetically useful new products. An array of interesting linear aminopolyhydroxylated structures was obtained by the combination of one or two cleavage steps from the tricycle, with overall very good acyclic selectivity, efficiency, and atom economy.

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Section: Resultsunclassified

Linear Aminopolyhydroxylated Structures Through Rapid Domino Assembly of a Highly Functionalized Heterotricyclic System and Its Selective Cleavage

1998

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“…Although cyclic nitronates are stable intermediates that can be converted to a variety of useful derivatives, such as alcohols, ketones, oximes, and amines [3b], their greatest potential lies in their ability to undergo [3 2] cycloadditions [5]. The 1,3-dipolar cycloaddition reaction of nitronates was first reported by Tartakovskii and co-workers in 1964 [6] and has subsequently been studied by Torssell [7], Carrie and co-workers [8], Seebach and coworkers [9], and others [10].…”

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Tandem Inter [4+2]/Intra [3+2] Cycloadditions of Nitroalkenes. Application to the Synthesis of Aminocarbasugars

Denmark

Juhl

2002

HCA

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Dedicated to Professor Dieter Seebach on the happy occasion of his 65th birthday The tandem inter [4 2]/intra [3 2] cycloaddition of nitroalkenes in the bridged mode was applied to the stereoselective synthesis of b-d-4-amino-2,4-dideoxycarbagulose, a representative aminocarbasugar. The synthesis required only five steps from known materials and delivered the protected aminocarbasugar (À)-20 in excellent yield (see Scheme 9). The success of the synthetic sequence relies on 1) the ability to incorporate Osubstituents at the nitroalkene moiety, 2) the identification of a suitably modified chiral dienophile, and in particular 3) the development of specific experimental conditions and protocols that allow for the formation and isolation of the highly sensitive nitroso acetals. The reduction of the C(1) carbonyl group of ()-19 gave unexpected stereoselectivity, which could be rationalized by a conformational inversion of the substrate (see Scheme 11).

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“…Rosini's group reported the first example of a silicon-tethered intramolecular 1,3dipolar cycloaddition 13 . The tricyclic compound was converted to the corresponding bicyclic diol by an oxidative removal of the temporary silicon linker.…”

Section: Scheme 8 Spiro Mode Intramolecular Cycloadditionsmentioning

confidence: 99%

“…H-NMR and13 C-NMR spectra were recorded on Joel 270 MHz and Varian 600 MHz spectrometers. Chemical shifts were reported relative to internal tetramethysilane ( 0.00 ppm) or CDCl 3 ( 7.26 ppm) for 1 H and CDCl 3 ( 77.0 ppm) for 13 C or CD 3 OD ( 4.87, 3.31 ppm) for 1 H and CD 3 OD ( 49.1 ppm) for 13 C. Melting points were measured on a Mel-Temp 1001D apparatus and uncorrected.…”

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Development of 1,2,3-triazole-borane complex as effective reagent for aldehyde/ketone reductive amination

Liao¹

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Synthesis of Isoxazoline-N-oxide through [3+2] Cycloaddition Wenyan Liao A catalytic cascade synthesis of Isoxazoline N-oxide was developed through prolinecatalyzed nitroalkene activation. A large variety of nitroalkenes and vinyl esters were suitable for this transformation, giving only trans isomer with good to excellent yields. Mechanistic studies revealed intramolecular cycloaddition as the rate-determining step. This strategy provided not only a new approach for the construction of substituted isoxazoline derivatives but further evidence of secondary amine nucleophilic activation of nitroalkene, an alternative path of proline catalysis. Development of 1,2,3-Triazole-Borane Complex as Effective Reagent for Aldehyde/Ketone Reductive Amination Wenyan Liao Air, moisture and thermally stable 1,2,3-triazole-boranes were successfully prepared and applied as reductants in aldehyde/ketone reductive amination with high efficiency and excellent substrate diversity. Detailed studies regarding to the reaction mechanism and application of this new reagent for other important transformations are currently under investigation in our group. iii DEDICATED TO My parents and my family iv ACKNOWLEDGEMENTS I would like to express my sincere gratitude to my advisor, Dr. Xiaodong Michael Shi, for his support, patience, and encouragement throughout my graduate studies. His mentorship was essential to the completion of this thesis and my graduate study.. My thanks also go to Dr. Kung Wang and Dr. George A. O'Doherty for their valuable comments that improved the contents of this thesis and their help during my time at WVU. I would also like to thank the former and present postdocs, Dr. Haifeng Duan (who helped me a lot during research and provided great contribution in my first project), Dr. Yuxiu Liu and Dr. Yunfeng Chen, my lab mates Cheng Zhong and Sujata Sengupta for their help both in my study and life. I want to thank all the faculty, staff and graduate students in Chemistry Department for their help in a variety of ways. Most importantly, I would like to thank my father Donghai Liao and my mother Baoyu Yang. Without their love and encouragement, I couldn't even survive in the foreign country. I would like to thank my parents-in-law, Lijuan Sun and Shengfu Zhong as well, who help me take care of my baby and my small family. Thanks to my dear daughter Sophia Zishan Zhong, I finished my own project after having her. Her cries and smiles enrich my life and give me strength to face the difficulties. The most special thanks will give to my husband Cheng Zhong for his love, understanding and precious help during the past few years. I would never forget the moment when he taught me to draw reaction mechanisms, revised my ppt slides, gave me research suggestions, took care of me when I was sick, and got up in the late night to change baby diapers. His support made this thesis possible. Thank you! Financial support from the National Science foundation, C.

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Silicon-Tethered 1,3-Dipolar Cycloaddition of 4-Hydroxy-2-isoxazoline 2-Oxides

Cited by 48 publications

References 9 publications

Linear Aminopolyhydroxylated Structures Through Rapid Domino Assembly of a Highly Functionalized Heterotricyclic System and Its Selective Cleavage

Linear Aminopolyhydroxylated Structures Through Rapid Domino Assembly of a Highly Functionalized Heterotricyclic System and Its Selective Cleavage

Tandem Inter [4+2]/Intra [3+2] Cycloadditions of Nitroalkenes. Application to the Synthesis of Aminocarbasugars

Development of 1,2,3-triazole-borane complex as effective reagent for aldehyde/ketone reductive amination

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